1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to a disk drive reading servo sectors (also known as “servo wedges”) in an interleaved fashion recorded at a relative offset on multiple disk surfaces to increase the servo sample rate.
2. Description of the Prior Art
The servo sample rate (frequency of sampled servo sectors) affects various aspects of a disk drive, including track misregistration (TMR), servo bandwidth, shock detection, and radial recording density or tracks-per-inch (TPI). Increasing the number of servo sectors per disk surface increases the servo sample rate but decreases capacity due to the overhead required to record each servo sector.
U.S. Pat. No. 5,936,790 discloses a disk drive which increases the servo sample rate by reading servo sectors from multiple disk surfaces while accessing a selected disk surface. One of the disk surfaces, referred to as the “master”, comprises significantly more servo sectors than the other disk surfaces, referred to as the “slaves”. While the disk drive is accessing a slave disk surface during a read/write command, the servo sectors recorded on the master disk surface are read and used to augment the servo data read from the servo sectors recorded on the slave disk surface. Although this technique increases the servo sample rate, the capacity of the master disk surface is reduced due to the increased number of servo sectors.
There is, therefore, a need to increase the servo sample rate in a disk drive without decreasing the capacity of any one of the disk surfaces.